>The SDK says there are stack operators s0...s49, l0...l49,>and sp0...sp49.>>That suggests to me that there are stack would hold 50 values. No, those are registers, not stack variables. Note my HP-15C had 20 general registers, 0 to 9, and .0 to .9. And, only four stack levels.>I would have thought that would be enough. An expression would>have to be very complicated to push 50 values on the stack>without popping any. Having said that, I wait for someone to>provide one! One of the MSFS bloggers experimented, and found the stack could hold up to 30 valuesoperators. He noted that the FS9 GPU used as many as 27. When I was learning 8087 coding I assumed loading variables on the stack simply pushed the top ones off. As in an HP RPN calculator. It was only after I got Code View that I saw loading one too many variables on the stack resulted in NAN's for later operations. So, I had to be careful not to load too many variables. I also used 'FINIT' before a block of NPX operations to be sure the stack was empty. 'c' clears the stack in XML RPN, and I put that at the start of every block. If one codes carefully, the stack should end up empty; but it's easy to leave some things on it. Ron

>Sorry I forgot to answer this:>>> Except from not showing does>>it still execute the code or does it skip the code all>>together? >> only affects outputs to FS, ie Image, String,>CustomDraws, Polys, etc.>If the last stack entry before the is EXACTLY 0,>those won't show; ANY other value and those will be visible.>The rest of the code in the , ie inside , etc,>will be executed no matter its condition; including>var and/or events assignments; etc.>>TomThanks Tom. I thought... "Noboddy has a clue." Anyway I know now!I stirred up quite a thing with this question. Interesting stuff!Roelof